Problems with upgrade to Surfboard SB8200 modem

I just upgraded by modem from Surfboard SB6141 to Surfboard SB8200. I can access internet when the coax cable is connected directly to the modem, Ethernet connected to the Netgear N900 Wi-Fi router, but I can't get a TV signal through my TiVo Roamio Pro (which I shouldn't). When I connect the coax cable from the wall to a two-way splitter with one coax going to the modem (ethernet cable connected to Wi-Fi router) and one coax going to TiVo, I get a TV signal, but no internet access. This is...

Problems with upgrade to Surfboard SB8200 modem

Problems with upgrade to Surfboard SB8200 modem